Question: Which of the following numbers is a factor of 50? ${4,5,7,8,11}$
Solution: By definition, a factor of a number will divide evenly into that number. We can start by dividing $50$ by each of our answer choices. $50 \div 4 = 12\text{ R }2$ $50 \div 5 = 10$ $50 \div 7 = 7\text{ R }1$ $50 \div 8 = 6\text{ R }2$ $50 \div 11 = 4\text{ R }6$ The only answer choice that divides into $50$ with no remainder is $5$ $ 10$ $5$ $50$ We can check our answer by looking at the prime factorization of both numbers. Notice that the prime factors of $5$ are contained within the prime factors of $50$ $50 = 2\times5\times5 5 = 5$ Therefore the only factor of $50$ out of our choices is $5$. We can say that $50$ is divisible by $5$.